Testing system and testing method for structure

ABSTRACT

The present invention discloses a testing system and a testing method for a structure which tests a structure made of a test piece structure and a numerical model virtually connected to the structure. A simulated structure including a frame, an actuator and a reaction force measuring device is mounted on a foundation on which a shaking table is also mounted. Only the test piece structure is mounted on the shaking table. The motion of the shaking table  5  which is generated at the time of shaking the test piece structure using the shaking table and the actuator is measured by a shaking table motion measuring device, while the reaction force generated by the test piece structure is measured by a reaction force measuring device. Using these measured values and the numerical model stored in a digital computer, the motion of the test piece structure after a predetermined period for the motion of the simulated structure is calculated. The actuator and the shaking table are driven so as to make this calculated motion.

This application is a divisional of application Ser. No. 09/339,874,filed Jun. 25, 1999, now U.S. Pat. No. 6,397,153.

BACKGROUND OF THE INVENTION

The present invention relates to a testing system and a testing methodfor a structure, and more particularly to a testing system and a testingmethod for a structure which can be preferably used for an earthquakeresistance test.

To evaluate the earthquake resistance of a structure, it becomesnecessary to evaluate not only the linear deformation of the structurebut also the non-linear deformation and the rupture phenomenon of thestructure. For this purpose, a testing method where a test is carriedout by combining the simulation of the behavior of the structure using acomputer and a shaking test which actually shakes a test piece using ashaking table and an actuator has been put into practice. This testingmethod has an advantage that it can carry out the test using the testpiece which has a size close to a size of an actual structure. However,since both the actuator and the test piece are mounted on the shakingtable, the actual situation is that the test piece which is mounted onthe shaking table must be small-sized compared to the size of theshaking table. Conventionally, at the time of testing a structure, thetest piece, the actuator for shaking the test piece and a reaction wallfor the actuator are all mounted on the shaking table. Such an exampleis described in JP-A-7-55630.

As described above, in the test which combines the simulation using thecomputer and the shaking test which tests the actual test piece usingthe shaking table and the actuator, the test can be carried out usingthe test piece having the size similar to that of the actual structure.However, in the testing method described in the known example whichmounts the reaction wall for the actuator on the shaking table the partof the shaking table is occupied by this reaction wall. Accordingly,only the remaining part of the shaking table can be used for the testpiece so that such a method is less optimal in view of the effective useof the shaking table. Therefore, the advantage that the large structurecan be tested is hampered and thus reducing the space for the reactionwall is required in terms of the preparation of the expensive shakingtable facilities.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above mentionedinconveniences and it is an object of the present invention to provide atesting system and a testing method which can sufficiently make use ofthe size of the shaking table and can carry out a test on a test piecehaving a size close to a size of an actual structure.

It is another object of the present invention to provide a testingsystem and a testing method for a structure which can make use of anentire space of the shaking table. Furthermore, the present inventioncan achieve the above objects with a simple constitution without addingany comprehensive modifications to a shaking table device.

The first aspect of the present invention to achieve the above objectsis that a testing system for a structure which tests a structure made ofa partial structure and a numerical model virtually connected to thispartial structure comprises a shaking table on which the partialstructure is mounted, a simulated structure which includes an actuatorfor shaking the partial structure and reaction force measuring means formeasuring a reaction force which it receives from the partial structurewhen the partial structure is shaken, and a digital computer whichcalculates the motion of the numerical model based on the measuredvalues of the reaction force measuring means and generates a shakingsignal for the actuator based on the calculated result, and the shakingtable and the simulated structure are mounted on a same foundation.

The second aspect of the present invention to achieve the above objectsis that the testing system comprises a shaking table which is mounted ona foundation by way of a first actuator, a simulated structure having atleast one second actuator which is fixedly mounted on a foundation whichis common to the foundation on which the shaking table is mounted, areaction force measuring device which measures a reaction forcegenerated by a test piece structure connected to the simulatedstructure, a digital computer which stores a numerical model virtuallyconnected to the test piece structure, a controller which controls thesimulated structure, and a shaking table motion measuring device whichmeasures the motion of the shaking table.

It is preferable that the digital computer outputs a control signal tothe controller based on outputs of the shaking table motion measuringdevice and the reaction force measuring device. It is also preferablethat the digital computer calculates the motion of the test piecestructure based on the output of the reaction force measuring device andthe numerical model, and includes an adder which adds the calculatedresult and the output of the shaking table motion measuring device, andoutputs the added result to the controller.

It is also preferable that the digital computer stores the shaking waveform of the shaking table, and the digital computer outputs a controlsignal to the controller based on the output of the reaction forcemeasuring device, and the digital computer includes time control meanswhich controls a shaking timing of the shaking table.

It is further preferable that the simulated structure is capable ofshaking having a plurality of degrees of freedom.

It is also preferable that the digital computer includes memory means towhich the numerical model is inputted, structure motion calculatingmeans which calculates the motion of the structure after a predeterminedperiod from the time when the reaction force is measured based on theoutputs of the reaction force measuring device and the shaking tablemotion measuring device with reference to the numerical model stored inthe memory means, shaking signal calculating means which calculates ashaking signal to be given to the actuator after a predetermined periodbased on the calculated motion of the structure, and time control meanswhich controls the predetermined time.

Furthermore, the digital computer may include means for storing theshaking wave form of the shaking table, while the time control meanscontrols the shaking timing of the shaking table based on this storedshaking wave form.

The third aspect of the present invention to achieve the above objectsis that in a testing method for a structure which tests a structure madeof a partial structure and a numerical model virtually connected to thispartial structure, the partial structure mounted on a shaking table isshaken by the shaking table and an actuator which is fixedly mounted ona foundation which is the same foundation on which the shaking table ismounted, a reaction force generated by the partial structure and adisplacement of the shaking table at this time are measured, a motion ofa joint between the numerical model and partial structure after apredetermined period from the time when the reaction force is measuredis obtained based on the measured values of the reaction force and thedisplacement of the shaking table, and a shaking signal is inputted tothe actuator for realizing the obtained motion at the joint after alapse of the predetermined time, and the actuator shakes the partialstructure based on this signal.

The fourth aspect of the present invention to achieve the above objectis that in a testing method for a structure made of a test piecestructure mounted on a shaking table and a numerical model virtuallyconnected to the test piece structure and stored in a digital computer,a step in which the test piece structure is shaken by the shaking tableand an actuator fixedly mounted on a foundation on which the shakingtable is mounted, and a reaction force generated by the test piecestructure is measured, a step in which a displacement of the shakingtable is measured, a step in which the measured value of the reactionforce is inputted to the digital computer, a step in which measureddisplacement of the shaking table is inputted to the digital computer, astep in which a relative motion of the structure to the shaking tableafter a predetermined period from the time when the reaction force ismeasured is calculated from the measured value of the reaction forcewith reference to the numerical model, a step in which a relative motionof the structure to the foundation for the shaking table after apredetermined period from the time when the reaction force is measuredis calculated by adding the calculated result of the relative motion ofthe structure and the measured value of the displacement of the shakingtable, a step in which a shaking signal which makes the motion obtainedby the calculation at a portion of the test piece structure to be shakenby the actuator is calculated, a step in which the shaking signal isoutputted after a predetermined period from the time when the reactionforce is measured, and a step in which the actuator is driven based onthe shaking signal are carried out in sequence.

The fifth aspect of the present invention to achieve the above objectsis that in a testing method for a structure made of a test piecestructure mounted on a shaking table and a numerical model virtuallyconnected to the test piece structure and stored in a digital computer,the test piece structure is shaken by using the shaking table and anactuator fixedly mounted on a foundation on which the shaking table ismounted, a reaction force generated by the test piece structure ismeasured and inputted to the digital computer while a relative motionbetween the structure and the shaking table after a predetermined periodfrom the time when the reaction force is measured is calculated usingthe measured value of reaction force with reference to the numericalmodel, a relative motion of the structure to the foundation for theshaking table after a predetermined period from the time when thereaction force is measured is calculated by adding the calculated resultof the relative motion of the structure and a preliminarily obtaineddisplacement of the shaking table, a shaking force given to the testpiece for making the calculated motion after the predetermined period isobtained, and this shaking force is generated by the actuator.

The preliminarily obtained displacement of the shaking table ispreferably measured at the time of measuring the reaction force orprestored in the digital computer. It is also preferable that thepreliminarily obtained displacement of the shaking table is the valuemeasured at the time of measuring the reaction force, and aftercalculating the relative motion between the structure and the shakingtable which is carried out after a predetermined period from the timewhen the reaction force is measured, when the motion of the structurerelative to the foundation for the shaking table after a predeterminedperiod is to be obtained, a prestored shaking wave form of the shakingtable is used, and the time lag is calculated from the differencebetween the measured value of the motion of the shaking table and theprestored wave form and the predetermined period is adjusted based onthe time lag to correct the predetermined period.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of one embodiment of the shaking test systemof the present invention.

FIG. 2 to FIG. 4 are schematic views of modifications thereof.

FIG. 5 is a flow chart of one embodiment of the shaking testing methodof the present invention.

FIG. 6 to FIG. 8 are flow charts of the modifications thereof.

FIG. 9 is a schematic view of one embodiment of the shaking testingsystem of the present invention showing the surroundings of the testpiece structure in detail.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention is hereinafter explained inconjunction with attached drawings.

FIG. 1 is a block diagram relating to one embodiment of a shakingtesting system for a structure according to the present invention. Forinstance, to examine the behavior of a bridge girder at the time of anoccurrence of an earthquake, it is impossible to examine the wholebridge girder. Accordingly, a method which cuts out a part of the bridgegirder as a test piece and analyzes the remaining portion of the bridgegirder numerically taking into account that the behavior of the motionof the remaining portion has a strong linearity is used. In such a case,a test piece structure 3 has one end thereof fixedly mounted on ashaking table 5 and the other end thereof connected to a frame 8provided to a front end portion of an actuator 1. The remaining portionsof the test piece structure 3 are not connected to any other members.Here, the actuator 1 is mounted on a rigid wall 7 which is fixedlymounted on a foundation 6 on which the shaking table 5 is also mounted.The actuator 1, the frame 8 and a reaction force measuring device 2constitute a simulated structure. The reaction force measuring device 2measures the reaction force applied to the test piece structure 3 byshaking. So long as the reaction force can be measured, the location ofthe reaction force measuring device 2 is not limited to a position shownin FIG. 1.

The shaking table 5 is shaken in upper and lower directions by means ofactuators 31, while the shaking table 5 is shaken in horizontaldirection consisting of an X direction and a Y direction by means ofactuators not shown in drawings. When the shaking table 5 is shaken bythese actuators, the reaction force loaded to the reaction forcemeasuring device 2 from the test piece structure 3 is transmitted tosignal input means 13 by way of signal transmission means 16 andeventually is inputted to a digital computer 10. When the shaking table5 is shaken, a motion value of the shaking table 5 measured by a shakingtable motion measuring device 4 is transmitted to signal input means 12by way of signal transmitting means 15 and this value is also inputtedto the digital computer 10. A shaking signal is transmitted from asignal output means 11 which includes the digital computer 10 to anactuator controller 9 by way of signal transmission means 14. Thesimulated structure is driven by this shaking signal. In case theshaking of the shaking table 5 in upper and lower directions is notnecessary, the actuators 31, may be replaced by a support device whichcan support the shaking table 5 in upper and lower directions.

In the above-mentioned constitutional components, to be more specific,the transmission signals are voltage signals, the signal transmissionmeans are cables, the signal input device is an A/D converter and thesignal output device is a D/A converter. However, the above-mentionedconstitutional elements are not limited to these parts but may be madeof other ways.

In the digital computer 10, the measured value of the motion of theshaking table 5 and the measured value of the reaction force which areinputted from the signal input means 12 and the signal input means 13respectively are outputted to structure motion calculating means 17. Anumerical model is inputted and stored in the structure motioncalculating means 17. This numerical model is a virtual structureconnected to the test piece structure 3 and is made of a matrix ofcoefficients and various constants of equations of motions and can bepreliminarily obtained by an auxiliary device of the digital computernot shown in drawings.

The structure motion calculating means 17 numerically integrates theequations of motion with the measured value of the reaction force as anexternal force using the numerical model. Thus, the condition of therelative motion between the numerical model and the shaking table isobtained by calculation. By combining the calculated result and themeasured value of motion of the shaking table 5, the condition of themotion of the numerical model relative to the foundation 6 after a givenperiod or a predetermined period from the time when the reaction forceis measured is obtained. Although the central difference method can bepreferably used as the numerical integration, the numerical integrationis not limited to such a method.

This calculated result is inputted to shaking signal calculating means18 and a shaking signal to the actuator 1 is generated such that after agiven period or a predetermined period, the motion of a joint betweenthe test piece structure 3 and the simulated structure 30 coincides withthe result calculated by the structure motion calculating means 17. Thisshaking signal is outputted from signal output means 11. The digitalcomputer 10 is controlled by time control means 19 such that theprediction of motion calculation of the test piece structure after alapse of a given time or a predetermined time is actually obtained afterthe given time or the predetermined time.

According to the present embodiment, even when the actuator is notmounted on the shaking table, an experiment can be carried out byemploying the simulation and the numerical calculation and hence, theexperiment which makes full use of the size of the shaking table becomespossible.

A modification of the above-mentioned invention is explained using ablock diagram shown in FIG. 2.

In the embodiment shown in FIG. 1, the signal measured by the measuringdevice 4 which measures the motion of the shaking table 5 is inputted tothe signal input means 12. However, in this modification, the signal isdirectly inputted to a signal adder 21 which is disposed between thesignal output means 11 and the controller 9 for the actuator 1. Thismodification is different from the embodiment shown in FIG. 1 on thispoint. Accordingly, the same parts which appear in the embodiment shownin FIG. 1 are given the same symbols. In the signal adder 21, based onthe measured value of the motion of the shaking table 5 measured by themeasuring device 4, the measured signal is converted to a shaking signalwhich makes the motion of the measured values. Parallel with the aboveoperation, a shaking signal transmitted from the digital computer 10 byway of the signal transmission means 14 is added to the previous shakingsignal and its output signal is inputted to the controller 9 for theactuator 1 by way of the signal transmission means 22.

According to this modification, even when the actuator is not mounted onthe shaking table, the testing of a structure becomes possible by thecombined use of the conventional simulation and the numericalcalculation.

Another modification of the present invention is explained using a blockdiagram shown in FIG. 3. The difference between this modification andthe above-mentioned embodiment is that this modification does not use anoutput of motion of the shaking table measured by the shaking tablemotion measuring device 4 for the control of the actuator 1.Accordingly, the motion of the shaking table must be simulated by anysuitable forms. In this modification, the wave form of the motion of theshaking table is preliminarily stored by an auxiliary device of thedigital computer such as memory means.

By combining the condition of the relative motion between the numericalmodel calculated by the digital computer 10 and the shaking table and apreliminarily inputted wave form of the motion of the shaking table, thecondition of the motion of the numerical model relative to thefoundation 6 after a predetermined period from the time when thereaction force is measured is obtained. Although, in FIG. 3, a case inwhich the time control means 19 controls the shaking table 5 is shown,the control range of the time control means 19 may be restricted withinthe digital computer 10 and the time control function that the shakingtable 5 has is used as time control means of an upper order.

According to this modification, a testing of a structure can be carriedout by only altering the programming of structure motion calculationmeans and adding time signal transmission means between the shakingtable and the time control means in a conventional earthquake resistancetesting method for the structure which uses the conventional simulationand the numerical calculation in parallel. Accordingly, the cost for thetest can be reduced and the test can be simplified.

Still further modification of the present invention is explained using ablock diagram shown in FIG. 4. This modification is characterized byproviding the time control relationship between the shaking table andthe time control means 19 shown in FIG. 1.

In the memory device of the digital computer 10, as in the case of themodification shown in FIG. 3, the numerical model and the wave form ofthe motion of the shaking table are stored. The condition of the motionof the shaking table relative to the foundation 6 after a predeterminedperiod from the time when the reaction force is measured is calculatedbased on the condition of the relative motion of the numerical model tothe shaking table which is calculated by the structure motioncalculating means 17 and the time lag between the preliminarily inputtedwave form of the motion of shaking table and the wave form of themeasured value of the motion of the shaking table. Here, the wave formof the motion of the shaking table at the time which precedes by thetime lag is obtained from the preliminarily stored wave form of themotion of the shaking table and the measured value is corrected by thisvalue. The relationship between the shaking table 5 and the digitalcomputer 10 is similar to that of the case shown in FIG. 3 and hence,the detailed explanation thereof is omitted. According to thismodification, the calculation of the motion of the structure higher thanthat of the embodiment shown in FIG. 1 can be achieved.

One embodiment and its respective modifications of the testing methodfor a structure which are carried out using the systems shown in theabove-mentioned embodiment and its respective modifications areexplained in detail in conjunction with FIG. 5 and ensuing drawings.FIG. 5 is shows an embodiment which uses the testing system for thestructure shown in FIG. 1. In this embodiment, an earthquake resistancetest of a structure is carried out in accordance with following steps.

(1) First of all, the actuators 31 or the like for the shaking table 5shake the test piece structure 3. The reaction force generated by thetest piece structure 3 is measured by the reaction force measuringdevice 2 (step 110).

(2) Simultaneously, the displacement of the shaking table 5 is measuredby the shaking table motion measuring device 4 (step 120).

(3) Subsequently, the reaction force value measured by the reactionforce measuring device 2 in the step 110 is inputted to the digitalcomputer 10 (step 130).

(4) The displacement of the shaking table measured by the shaking tablemotion measuring device 4 in the step 120 is inputted to the digitalcomputer 10 (step 140).

(5) Based on the numerical model of the structure preliminarily inputtedto the digital computer 10, the structure motion calculating means 17calculates the motion of the structure after a predetermined period fromthe time when the reaction force is measured using the reaction forcevalue measured in the step 110. Here, the structure is comprised of thenumerical model and the test piece structure 3, while the motion meansthe relative motion between the structure and the shaking table 5 (step150).

(6) The structure motion calculating means 17 adds the measured value ofthe displacement of the shaking table obtained in the step 140 to themotion of the structure obtained in the step 150 and calculates themotion of the structure after a predetermined period from the time whenthe reaction force is measured. Here, the motion means the motion of theshaking table 5 relative to the foundation, namely, the absolutedisplacement (step 160).

(7) Based on the calculated result of the motion of the structureobtained in the step 160, the shaking signal calculating means 18calculates a shaking signal for the actuator 7 which is necessary forobtaining the condition of the motion to be made by the simulatedstructure 30 (step 170).

The signal output device 11 outputs the shaking signal obtained in thestep 170 after a predetermined period (step 180).

(8) Based on the shaking signal outputted from the signal output device11, the controller 9 drives the actuator 1 (step 190).

(9) Here, the completion or the end of the shaking test for a structureis determined whether a preliminarily set time has lapsed or not orwhether a stop signal is given to the actuator controller or not. Thisdetermination means may be incorporated in the digital computer 10 orthe actuator controller 9 or may be provided as a separate device.

According to this embodiment, due to the combined use of the shakingtest of the partial structure and the numerical calculation using thenumerical model, the earthquake resistance test for a structure becomespossible without mounting the actuator on the shaking table and hence,the entire space of the shaking table can be effectively used.Accordingly, the ratio between the mounting area for the partialstructure and the area of the shaking table can be made as close aspossible to 1.

Subsequently, the modification of the testing method for a structureusing the testing system for a structure shown in FIG. 2 is explained inview of FIG. 6. This testing method differs from the above-mentionedembodiment in that the displacement of the shaking table 5 and thedisplacement of the actuator 7 are separated. To be more specific, Inthe testing method shown in FIG. 5, the steps 150-170 are replaced withthe following steps 210-230 and steps 270, 280 and steps 250, 260 areadded.

(5a) Based on the numerical model of the structure preliminarilyinputted to the digital computer 10, the motion of the structure after apredetermined period from the time when the reaction force is measuredis calculated using the reaction force value measured in the step 110.Here, the motion of the structure means the relative motion between thestructure and the shaking table 5 (step 210).

(6a1) From the calculated result of the motion of the structure obtainedin the step 210, the shaking signal calculating means 18 calculates ashaking signal for the actuator 1 necessary for obtaining the conditionof the motion to be made on the simulated structure 30 after apredetermined period (step 220).

(6a2) The signal output device 11 outputs the shaking signal obtained inthe step 220 after the predetermined period (step 230).

Furthermore, parallel to the above-mentioned steps for shaking the testpiece structure, steps for controlling the displacement of the shakingtable 5 are carried out.

(4a1) The measured value of the displacement of the shaking tableobtained in the step 120 is inputted to the adder 21 by way of thesignal transmission means 15 (step 250).

(4a2) In the adder 21, based on the displacement of the shaking tablemeasured by the shaking table motion measuring device 4, a secondshaking signal for shaking the shaking table after the predeterminedperiod is obtained and the adder 21 outputs this second shaking signal(step 260).

(6a3) A first shaking signal of the structure obtained by the digitalcomputer 10 is inputted to the adder 21 (step 270).

(7a) The first shaking signal of the structure obtained by the digitalcomputer 10 and the second shaking signal are combined in the adder 21and are converted to a third shaking signal (step 280).

According to this modification, while using the conventional shakingtable without any change, due to the combination of the shaking test ofthe partial structure and the numerical calculation of the numericalmodel, the earthquake resistance test for a structure can be carried outwith a high precision.

The modification of the testing method for a structure using the testingsystem for a structure shown in FIG. 3 is explained in view of FIG. 7.This testing method differs from the above-mentioned modification shownin FIG. 5 in that the method does not use the output of the shakingmotion measuring device. Namely, the motion of the shaking table 5 isstored in memory means and based on this stored motion, the time controlmeans 19 controls the motion of the shaking table 5. Accordingly, in thesteps 110-160 of the first shaking test embodiment, the steps 120 and140 are omitted and the steps 150 and 160 are changed to the followingsteps 310, 320.

(5b) With respect to the numerical model of the structure which isprestored in the digital computer 10, the structure motion calculatingmeans 17 calculates the relative motion of the structure to the shakingtable after a lapse of a predetermined period from the time when thereaction force is measured (step 310).

(6b) By adding a preliminarily stored or inputted shaking wave form ofthe shaking table to the calculated result of the motion of thestructure obtained in the step 310 using the structure motioncalculating means 17, the motion of the structure relative to thefoundation for the shaking table after the predetermined period from thetime when the reaction force is measured is calculated (step 320).

Thereafter, the step 170 and ensuing steps are carried out. According tothis modification, in addition to the advantage of the embodiment of thefirst testing method, by merely adding the signal transmission means forperforming the time control between the shaking table and the digitalcomputer to the conventional shaking table and altering the programmingrelated to such an addition, an earthquake resistance test of alarge-scaled structure can be carried out using the simple numericalmodel and the partial structure.

The modification of the testing method for a structure using the testingsystem for a structure shown in FIG. 4 is explained in view of FIG. 8.This testing method is characterized by adding a time control of theshaking table to the testing method shown in FIG. 5. Namely, in place ofthe step 160, steps 410-430 are carried out.

(6c1) Based on the shaking wave form of the shaking table which ispreliminarily inputted to the digital computer 10, the displacement ofthe shaking table after a predetermined period from the time when thereaction force is measured is obtained. By combining this value and thecalculated result of the relative motion of the structure after thepredetermined period, the structure motion calculating means calculatesthe motion of the structure relative to the foundation for the shakingtable after the predetermined period (step 410).

(6c2) By comparing the preliminarily inputted shaking wave form of theshaking table with the measured value measured by the shaking tabledisplacement measuring means 4, the structure motion calculating meanscalculates the time lag between the wave form obtained by plotting themeasured values measured by the shaking table displacement measuringmeans 4 at a predetermined time interval and the shaking wave form ofthe shaking table (step 420).

(6c3) Based on the time lag obtained in the step 420, the time controlmeans 19 adjusts the predetermined time interval from the time when thereaction force is measured necessary for calculating the absolutedisplacement of the structure, and renews the predetermined timeinterval (step 430).

According to this testing method, an earthquake resistance test can becarried out with a higher precision.

Although the actuator 1 is described as an actuator havingone-dimensional excitation capability in any one of the above-mentionedtesting methods, it is needless to say that the actuator 1 may be anactuator having two or more-dimensional excitation capability.Furthermore, the shaking direction of the shaking table may be eitherone horizontal direction or two horizontal directions, or the shakingmay be generated by applying impacts on the shaking table. Stillfurthermore, the predetermined period can be a fixed time or a valuecalculated by the computer.

Furthermore, in FIG. 9, a case where the structure is shaken by aplurality of actuators is shown. The test piece structure 3 is mountedon the shaking table 5 and is shaken in vertical directions by twoactuators 1, and in a horizontal direction by one actuator 1. Althoughnot shown in drawings, the shaking table 5 is provided with shakingmeans in respective directions for enabling the shaking of the shakingtable 5 in vertical directions as well as in horizontal directions. Asmentioned previously, the reaction forces applied to the actuators 1,from the test piece structure 3 are measured by the reaction forcemeasuring device 2, while the motion of the shaking table 5 is measuredby the shaking table motion measuring device 4. The construction ofother components or parts is the same as that of the above mentionedembodiments and modifications and hence, the detailed explanation isomitted. According to this embodiment, since the structure is shakenwith a plurality of degrees of freedom using a plurality of actuatorsand hence, more actual or realistic simulation test can be carried out.Although the part which constitutes the numerical model is omitted inFIG. 9, it is needless to say that a so-called hybrid shaking test iscarried out using the numerical model.

Although respective embodiments and respective modifications of thepresent invention have been explained heretofore, the present inventionsubstantially can take various forms within its scope without departingfrom the gist of the invention. Accordingly, the previously mentionedembodiments and modifications are simply illustrations of the presentinvention in any aspects and they should not be construed to limit thepresent invention. Furthermore, modifications which belong to a scope ofequivalence of the claims fall within the scope of the presentinvention.

According to the present invention, when the partial structure mountedon the shaking table is shaken by the shaking table and the actuatorswhich are fixedly mounted on the foundation on which the shaking tableis also mounted, the shaking response of the structure made of thepartial structure and the numerical model virtually connected to thepartial structure is calculated by the digital computer and thecalculated result is made by the shaking table and the actuator andhence, the test of the large-sized test piece structure which makes fulluse of the size of the shaking table can be carried out.

What is claimed is:
 1. A testing system for a structure comprising: ashaking table mounted on a foundation by way of a first actuator; asimulated structure having at least one second actuator fixedly mountedon the foundation and separately from the shaking table; a reactionforce measuring device to measure a reaction force generated by a testpiece structure connected to the simulated structure; a digital computerwhich stores a numerical model that is virtually connected to the testpiece structure; a controller to control the simulated structure; and ashaking table motion measuring device to measure motion of the shakingtable, wherein the digital computer includes time control means tocontrol a shaking timing of the shaking table and means for storing ashaking wave form of the shaking table, and the digital computer outputsa control signal to the controller based on the output of the reactionforce measuring device.
 2. A testing system for a structure according toclaim 1, wherein said digital computer includes time control means whichcontrols the shaking timing of said shaking table and stores the shakingwave form of said shaking table, and said digital computer outputs acontrol signal to said controller based on the out put of said reactionforce measuring device.
 3. A testing system for a structure according toclaim 1, wherein said simulated structure is capable of shaking having aplurality of degrees of freedom.
 4. A testing system for a structureaccording to claim 1, wherein said digital computer includes memorymeans to which said numerical model is inputted, structure motioncalculating means which calculates the motion of said structure after apredetermined period from the time when the reaction force is measuredbased on the outputs of said reaction force measuring device and saidshaking table motion measuring device with reference to said numericalmodel stored in said memory means, shaking signal calculating meanswhich calculates a shaking signal to be given to said actuator after apredetermined period based on the calculated motion of said structure,and time control means which controls the predetermined period.
 5. Atesting system for a structure according to claim 4, wherein saiddigital computer includes means for storing the shaking wave form ofsaid shaking table, and said time control means controls the shakingtiming of said shaking table based on said stored shaking wave form. 6.A testing system for a structure according to claim 1, wherein thesimulated structure is adapted to be shaken over a plurality ofdirections.
 7. A testing system for a structure according to claim 1,wherein the digital computer includes memory means to which thenumerical model is inputted; means to calculate motion of the structureafter a predetermined period from the time when the reaction force ismeasured based on outputs of the reaction force measuring device and theshaking table motion measuring device with reference to the numericalmodel stored in the memory means; means to calculate a shaking signal tobe given to the actuator after the predetermined period based on thecalculated motion of the structure; and time control means whichcontrols the predetermined time.
 8. A testing system for a structureaccording to claim 7, wherein the time control means controls a shakingtiming of the shaking table based on the stored shaking wave form.